Duty cycle distortion is a common problem in many optical driver and receiver circuits, as well as in other types of circuits. Duty cycle distortion in an optical driver or receiver circuit may, for instance, be the result of asymmetrical rise and fall times in a typical optical data signal.
In accordance with the teachings described herein, systems and methods are provided for automatically correcting duty cycle distortion. A slicer may be used to receive a data input signal and compare the data input signal with a slicer offset voltage to generate a sliced data signal. The slicer may also receive an offset control signal to automatically adjust the slicer offset voltage. A phase detector may be used to receive the sliced data signal and a recovered clock signal and to compare the sliced data signal with the recovered clock signal to generate a rising edge output signal and a falling edge output signal. The rising edge output signal may correspond to a phase difference between a rising edge of the sliced data signal and an edge of the recovered clock signal. The falling edge output signal may correspond to a phase difference between a falling edge of the sliced data signal and an edge of the recovered clock signal. A first feedback circuit may be used to phase-lock the recovered clock signal to the sliced data signal utilizing at least one of the rising edge output signal and the falling edge output signal. At least one of the rising edge output signal and the falling edge output signal may be configured in a second feedback circuit to generate the offset control signal.